Screw-threaded fastening.



C. F. JOHNSON. SCREW THREADED FASTENLNGx APPLICATION FILED SEPT. a.1914.

Patented Apr. 15, 1919.

l'lozswlj D con U-ivrrED lSTATES vPATENT o1n'. nt.Y

CAEL E.. JOHNSON, or MILWAUKEE, wIscONsIN, AssIeNOE ro JOHNSON sEEvIoEcomm, or MILWAUKEE, wxsOONs'IN, A GORPOEATION or wrscoNsIN.

'SCREW-THREADED FASTENIN'G.

To all whom t may concern Be it known that I, CARL F. JOHNSON, a citizenofthe United States, residing v at Milwaukee,in the countyV of Milwaukeeand State of Wisconsmhavle invented certain new and useful Improvementsin Screw- Threaded Fastenings, of which the follow ing` is aspecification.

- ing a novel driving contact, so formed and so related to the objectheld by the screw that the latter may be removedmnly by means of aspecial key or vwrench provided `for the purpose.

The object of the. invention is topprovide'v a device of this classwhich is peculiarly diiiicult to turn with any implement etherI larger'-in diameter than thev head of the annular flange of a circular socketwrench,

which enters into locking engagement-withthe-screw by means oi. aneccentric long1.

tudinal pin. 'The counter-'sinking of the head prevents the releasing ofthe screw by. means of pliers, while the use o f a smgle and onlyslightly eccentric opening in the head 'prevents the use of this asthe-sole means of turning the screw. It is possible by carefulproportioning of the parts to produce ascrew wihich can be removed 'onlywith the specially designed wrench whic r accurately fits the screwhead.

Preferred embodiments of the-invention are illustrated in theaccompanymg draw gure 1 is an axial section through a screw embodying minventiomshowingthe ',lsameuin position wi the wrenchapplied;

mrtly 1n elevation, showing the vfrom j each his invention relates toscrew. threaded fastenings and particularly to a scnew hav-vA .roundedsurface as on ashar the screw, such 'recess' being only slightly Bist-aview longitudinal sec-'- Specification or Letters Patent. Patented Apr,15, 1919, Application led September 8, 1914. Serial No. 860,047. I

Fig. 4 is a perspective View of the screw i land wrench; and

Flg. 5 1s a view similar to Fig. 3 illustrat' Gis providedwithcountersunk aperture 8 andthe piece 7 with a threaded hole 9 toreceive the threaded portion 10 of the screw. The head 11 ofthe screw iscylindrical in shape. and is preferably slightly rounded at its upperedge 12,V in order to prevent the successful use of a taper socketwrench or the hke, as this will not hold so well on ,a

edge.

Ace

.A longitudinal hole'13 whlch is eccentric 70 with respect to the axisof the screw extends from the head 1'1 to the end of the threadedportion of the screw. It is not essential however that this hole extend.the entire length of the screw provided it i's given sufficient depth toreceive the wrench pin and hold the same firmly.; When the 4screw is ,inplace the head 11 lies wholly within'the l countersunk 'recess 8 of thepiece 6,"o'nly a very small annular space intervening be- -tween thescrew head and the sidesvof the recess. To turn the screw, I make use ofa wrench having 'a stem 14 and a cylindrical socket 15 whose annularyrim extends into the space -between the sides of the head 11 and thewalls of the countersunk recess 8. This wrench carries an eccentriclongitudinal pin 16 the eccentricity of the pin 16 being the same asthat of the hole 13 of the screw and when the wrench is applied to theAscrew head the pin 16 is the means by which thel screwis turned. Thewrench may be provided with a milled head 17 or any other suitable meansfor turning it.l

' In Figs. 1 to 4 the invention is illustrated as applied to a verysmall machine screw, the drawm 'being on anenlarged scale. The device asa particular advantage in small size screws because the screw hassuiicient frictional engagement with the pin 16 to be held thereby sothat a ready means of hold'- in the screw' during insertion is provided.

n Fig. 5, I illustrate the device as applied to a button head screw, orother screw having a substantially hemispherical head.. These Screws,111e the mes sewn in Figs. 11

to 4, are preferably mounted in countersunk holes and for similarreasons, but as the hemispherical hea'd oilers very little opportunityfor the use of pliers or taper socket wrenches, this latter form issometimes preferable where extreme safety against removal is necessary.Obviously the form shown in 1 very heavy. Similarly as the flange l5 isin contact with the head 11 all around the same itto'o can be maderelatively thin, so that onl a very slight space between the head 11 anvthe sides of the countersunk recess 8 is necessary. Consequently, andthis is particularly true in the smaller sizes, there is no opportunityfor the insertion of pliers or other clamping devices while the hole 13may be made so small that it offers no adequate means for turning thescrew except by means of the particular type of wrench illustrated andso proportioned as to tit the screw accurately. In other words the artsmay be so nicely proportioned that on y a closely fitting key will havestrength suiicient to turn the screw.

The embodiment shown in Fig. 5 may be similarly designed.

Having thus described my invention, what I claim is 1. As a new articleof manufacture, a screw .having a threaded body and a driving endportion of substantially circular con; tour, said driving portionprovided with one and only one longitudinal hole located eccentricallywith reference to the axis of the screw.

2. The combination of a screw having a single longitudinal holeeccentric with re spect to the axis of the screw, and having a drivingend\ portion of circular contour; and a removable driving key therefor,having an eccentric pin adapted to enter the hole in said screw, andhaving a circular projec- 'tion adapted to mate with the driving endportion of the screw to hold the screw and key in axial alinement.

3. The combination of a member having a threaded hole; a member having acountersunk hole; a screw holding said members together and having aheadlying substantially entirely Within said countersink and nearly butnot quite filling the same in the direction of its diameter, said screwhaving a single eccentric hole in its exposed end; and a turning keyhaving. a thin flange adapted to embrace the head of said screw withinsaid countersink and having an eccentric pin adapted to enter the holein said screw.

4. In combination with a body having a screw seat, the outer portion ofwhich seat is of slightly larger diameter than the screw it is toreceive; a screw adapted to fit and fill the lower or inner portion ofsaid seat but to leave an annular space about its outer or head portion,said screw having an eccentric hole or socket parallel with itslongitudinal axis; and an implement for turning said screw, having anannular rim or flange to (it the screw-head and occupy the annular spaceabout said head, and having also an eccentric pin to enter the hole orsocket in the screw.

Inftestimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

CARL F. JOHNSON.

Witnesses:

HELEN Go'i'rsLEBEN, L. M. WALSH.

